1. Field of the Invention
The present invention relates to improvements in surface mount components for electrical circuits handling microwave frequencies with signal paths that cross in proximity each other. More particularly, the invention relates to improvements particularly suited for multiple layer circuits requiring high signal quality and low profile applications. In particular, the present invention relates specifically to a particular surface mount construction of a crossover apparatus and method minimizing disruptions to the electrical signals.
2. Description of the Known Art
As will be appreciated by those skilled in the art, signal path crossings or crossovers are known in various forms. Patents disclosing information relevant to signal path crossovers include: U.S. Pat. No. 2,860,305, issued to Bey on Nov. 11, 1958 entitled High frequency transmission line coupling device; U.S. Pat. No. 3,104,363, issued to Butler on Sep. 17, 1963 entitled Strip transmission line crossover having reduced impedance discontinuity; U.S. Pat. No. 3,740,678, issued to Hill on Jun. 19, 1973 entitled Strip Transmission Line Structures; U.S. Pat. No. 4,078,214, issued to Beno on Mar. 7, 1978 entitled Microwave crossover switch; U.S. Pat. No. 4,533,883, issued to Hudspeth, et al. on Aug. 6, 1985 entitled Coaxial transmission line crossing; U.S. Pat. No. 5,003,273, issued to Oppenberg on Mar. 26, 1991 entitled Multilayer printed circuit board with pseudo-coaxial transmission lines; U.S. Pat. No. 5,321,375, issued to Corman on Jun. 14, 1994 entitled RF crossover network; U.S. Pat. No. 5,600,285, issued to Sachs, et al. on Feb. 4, 1997 entitled Monolithic stripline crossover coupler having a pyramidal grounding structure; U.S. Pat. No. 6,097,260 issued to Whybrew, et al. on Aug. 1, 2000 entitled Distributed ground pads for shielding cross-overs of mutually overlapping stripline signal transmission networks; U.S. Pat. No. 6,734,750, issued to Ostergaard on May 11, 2004 entitled Surface mount crossover component; U.S. Pat. No. 6,825,749, issued to Lin, et al. on Nov. 30, 2004 entitled Symmetric crossover structure of two lines for RF integrated circuits. Each of these patents is hereby expressly incorporated by reference in their entirety.
These patents teach various structures for crossovers but fail to recognized a simple construction approach with integrated capacitors and a construction that eliminates excess unwanted signal paths. Thus, these prior references are very limited in their teaching and utilization, and an improved microwave crossover is needed to overcome these limitations.